is FNB really charging its black customers higher interest rates than its white customers

i have been hearing allegations on social media about FNB charging its black customers up to 40% higher interest rates than whites especially. as i FNB home loan owner i was wondering if this is something that ohter black FNB homeloan owners have been worried about. i have been banking with FNB for many years and yet they granted me a home loan interest rate that is above prime, and apparently the allegation are around black South Africans being higher risk for credit. one of my new young colleagues just got an home loan from Nedbank for prime less than 2% and they are new customers with them. im just wondering if its advisable keeping my home loan with this bank long term as i did recently ask them for an interest rate review and they still claimed this is the best in the market